The CDC said in a document published Friday that it has “repeatedly documented” instances of the virus spreading through the air to people who were more than six feet away “under certain preventable circumstances.” This marks a change for the agency that previously said most infections took place through “close contact, not airborne transmission.”.

“COVID-19 spreads when an infected person breathes out droplets and very small particles that contain the virus.

Despite the change, some aerosol experts continue to say the CDC hasn’t gone far enough because it continues to say that transmission from far away is “uncommon,” which Marr said was “misleading and potentially harmful” because “if you’re in a poorly ventilated environment, virus is going to build up in the air, and everyone who’s in that room is going to be exposed.” The CDC’s wording “will lead people to continue to think that maintaining distance is sufficient to prevent transmission,” reads an open letter signed by seven experts, including Marr.

It can easily happen indoors in a poorly ventilated environment, when people are not wearing masks.”.

The change in wording has important implications and illustrates how good ventilation in indoor spaces is key to prevent transmission of the virus and people can stop worrying about cleaning surfaces so much.

Instead of blanket rules on gatherings, we would have targeted conditions that can produce superspreading events: people in poorly ventilated indoor spaces, especially if engaged over time in activities that increase aerosol production, like shouting and singing.